Interpretive Summary: Sarcocystis species are single celled parasites that cause illness in humans and livestock. Humans can become infected with this parasite by ingesting infected pork and beef. Cattle and pigs can become infected by ingesting food and water contaminated with the resistant parasite stages excreted in feces of infected humans.Many species of Sacrcocystis are pathogenic to animals.
Scientists at the Beltsville Agricultural Research Center and University of Minnesotta report diagnosis of a previously unrecognized species os Sarcocystis in a bald eagle.The results will be of interest to biologists, parasitologists, public health workers,and veterinarians.

Technical Abstract:
Protozoal meningoencephalitis is rare in raptors. An adult female bald eagle (Haliaeetus leucocephalus) with progressive neurological signs was euthanized after several months of treatment. The predominant histological lesion was lymphoplasmacytic and histiocytic meningoencephalitis involving the cerebrum and cerebellum. In addition, there was a marked segmental loss of granular cells and Purkinje cells as well as segmental atrophy of the molecular layer in the cerebellum. Protozoal merozoites and schizonts were observed in the gray matter of the cerebellum. Ultrastructurally, the merozoites were classified as a species of Sarcocystis due to the lack of rhoptries. Immunohistochemistry revealed positive reaction ( change throughout—it is not a stain)for Sarcosytis neurona, and the examined sections were negative for Toxoplasma gondii and Neospora caninum. Sarcocystis neurona-like infection may be considered as a differential diagnosis in bald eagles with chronic neurological disease.